title: Rab5 activation promotes focal adhesion disassembly, migration and invasiveness in tumor cells.
abstract: Migration and invasion are essential steps associated with tumor cell metastasis and increasing evidence points towards endosome trafficking being essential in this process. Indeed, the small GTPase Rab5, a crucial regulator of early endosome dynamics, promotes cell migration in vitro and in vivo. Precisely how Rab5 participates in these events remains to be determined. Considering that focal adhesions represent structures crucial to cell migration, we specifically asked whether Rab5 activation promoted focal adhesion disassembly and thereby facilitated migration and invasion of metastatic cancer cells. Pulldown and biosensor assays revealed that Rab5-GTP loading increased at the leading edge of migrating tumor cells. Additionally, targeting of Rab5 by different shRNA sequences, but not control shRNA, decreased Rab5-GTP levels, leading to reduced cell spreading, migration and invasiveness. Re-expression in knockdown cells of wild-type Rab5, but not the S34N mutant (GDP-bound), restored these properties. Importantly, Rab5 association with the focal adhesion proteins vinculin and paxillin increased during migration, and expression of wild-type, but not GDP-bound Rab5, accelerated focal adhesion disassembly, as well as FAK dephosphorylation on tyrosine 397. Finally, Rab5-driven invasiveness required focal adhesion disassembly, as treatment with the FAK inhibitor number 14 prevented Matrigel invasion and matrix metalloproteinase release. Taken together, these observations show that Rab5 activation is required to enhance cancer cell migration and invasion by promoting focal adhesion disassembly.
authors.affiliation: Department of Basic and Communitarian Sciences, Faculty of Dentistry, Universidad de Chile, Santiago 8380-492, Chile.
authors.forename: Pablo
authors.initials: P
authors.lastname: Mendoza
authors.forename: Rina
authors.initials: R
authors.lastname: Ortiz
authors.forename: Jorge
authors.initials: J
authors.lastname: Díaz
authors.forename: Andrew F G
authors.initials: AF
authors.lastname: Quest
authors.forename: Lisette
authors.initials: L
authors.lastname: Leyton
authors.forename: Dwayne
authors.initials: D
authors.lastname: Stupack
authors.forename: Vicente A
authors.initials: VA
authors.lastname: Torres
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology*; D045744:Cell Line, Tumor; D002465:Cell Movement; D004789:Enzyme Activation; D005260:Female; D022001:Focal Adhesions / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D051419:Paxillin / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D016596:Vinculin / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D051419:Paxillin; D034741:RNA, Small Interfering; D016596:Vinculin; D020696:rab5 GTP-Binding Proteins
keywords: Cell migration; Focal adhesion; Invasion; Rab5